CVE-2026-28490— Authlib Vulnerable to JWE RSA1_5 Bleichenbacher Padding Oracle
Quick assessment
Affected
authlib authlib
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.
Authlib是Authlib开源的一个构建 OAuth 和 OpenID Connect 服务器的终极 Python 库。 Authlib 1.6.9之前版本存在加密问题漏洞，该漏洞源于JSON Web Encryption RSA1_5密钥管理算法实现存在加密填充预言机漏洞，可能破坏底层密码库的恒定时间缓解措施。
Possible ATT&CK Techniques 1 AI
T1190 · Exploit Public-Facing Application
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I. Basic Information for CVE-2026-28490
Vulnerability Information
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Vulnerability Title
Authlib Vulnerable to JWE RSA1_5 Bleichenbacher Padding Oracle
Source: CVE Program / CVE List V5
Vulnerability Description
Authlib is a Python library which builds OAuth and OpenID Connect servers. Prior to version 1.6.9, a cryptographic padding oracle vulnerability was identified in the Authlib Python library concerning the implementation of the JSON Web Encryption (JWE) RSA1_5 key management algorithm. Authlib registers RSA1_5 in its default algorithm registry without requiring explicit opt-in, and actively destroys the constant-time Bleichenbacher mitigation that the underlying cryptography library implements correctly. This issue has been patched in version 1.6.9.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
通过差异性导致的信息暴露
Source: CVE Program / CVE List V5
Vulnerability Title
Authlib 加密问题漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Authlib是Authlib开源的一个构建 OAuth 和 OpenID Connect 服务器的终极 Python 库。 Authlib 1.6.9之前版本存在加密问题漏洞，该漏洞源于JSON Web Encryption RSA1_5密钥管理算法实现存在加密填充预言机漏洞，可能破坏底层密码库的恒定时间缓解措施。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)
Affected Products
II. Public POCs for CVE-2026-28490
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Patches & Fixes for CVE-2026-28490 (1)
Vendor Advisories for CVE-2026-28490 (1)
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JWE RSA1_5 Bleichenbacher Padding Oracle · Advisory · authlib/authlib · GitHub x_refsource_CONFIRM
Vendor Pages for CVE-2026-28490 (1)
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Release v1.6.9 · authlib/authlib · GitHub x_refsource_MISC
Same Patch Batch · authlib · 2026-03-16 · 3 CVEs total
| CVE-2026-27962 | 9.1 CRITICAL | Authlib JWS JWK Header Injection: Signature Verification Bypass |
| CVE-2026-28498 | 8.2 HIGH | Authlib: Fail-Open Cryptographic Verification in OIDC Hash Binding |
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V. Comments for CVE-2026-28490
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